The suppression of tremors in the extremities of human beings.
The present invention relates to a method and apparatus for treating tremors in the extremities of humans. Tremors in humans are associated with several medically defined disorders. One such disorder is Essential tremor. Parkinson""s disease is another such disorder. Those who suffer from such disorders experience excessive and involuntary oscillation of their limbs, which results in loss of control of attempted performance of an action or attempted maintenance of a postural position.
Present methods of treating such tremor disorders include medication such as Propranolol, Primidone, and Benzodiazepines, but these are often poorly tolerated and/or lose efficacy with prolonged treatment. A procedure known as xe2x80x9cdeep brain stimulationxe2x80x9d has also been used with some success, but it is not effective for some patients and has the disadvantages of high expense and the risk of intracerebral hemorrhage or stroke. In addition, this procedure, which involves drilling a hole through the skull and into the brain, is subject to the difficulty that gaining access to the desired part of the brain is more difficult in some subjects that others.
Historically, deep brain stimulation has involved the creation of subcortical lesions in the thalamus and, in some cases, in the ansa lenticularis. Other tremor disorders that have been found to respond to a lesion in the thalamic area, particularly in the ventrolateral nucleus of the thalamus or just anterior to the posterior ventral lateral nucleus, are, in addition to Parkinson s disease and Essential cerebellar tremors, dystonia musculorum deformans, hemiballismus, tardive, dyskinesia, and chorea. However, given the fact that deep brain stimulation is drastic surgery, it is often not used with patients who have relatively mild tremor systems.
In this regard, some diseases which produce tremor symptoms are progressive at a relatively rapid rate, e.g., Parkinson""s disease, while others are not, e.g., Essential tremors.
Given the fact that medication has proved unsatisfactory as a treatment for tremors and given the further fact that drastic surgery such as deep brain stimulation is not generally used to treat mild tremors, a need for a method and means for effectively treating mild tremors as a stand-alone treatment or as an adjunct to other treatments has long existed, as well as a similar need for effectively treating severe tremors.
The precise pathophysiology of Essential tremor is unknown, but it is believed to involve the cerebellum. The cerebellar outflow to the thalamus appears to be critical, and the cerebellar-thalamic projection site is the frequent target of neurosurgical therapies for intractable Essential tremor. Thus, similarity to the surgical treatment for intractable tremor in Parkinson""s disease can be seen.
The peripheral nervous system appears to play a critical role in Essential tremor. Beta-adrenergic receptor blocking medications that do not block the brain have some efficacy against this disorder. Essential tremor patients, like those with focal dystonia, often utilize xe2x80x9csensory tricksxe2x80x9d such as touching the chin to suppress tremor, or touching the dorsum of the hand to suppress writing tremor. During the act of writing, it has been observed that tremor worsened if the hand is not permitted to touch the writing surface, such that afferent sensory information about the position of the hand is minimized. Such maneuvers may well enhance musculotendinous afferents to the cerebellum, thereby suppressing tremor.
The present invention provides a non-invasive method of controlling tremor. While the exact mechanism of the present invention is not known with certainty, it is believed likely that enhancement of muscular and tendon afferent sensory function is involved.
In any event, the present invention involves the application of external pressure to certain areas of the patient""s body to control tremor. Preferably, this pressure is applied by using a pressure-applying cuff. It is believed that such pressure activates musculotendonis afferents with the result that tremor is controlled or suppressed, but the present invention is not to be tied to that belief.
The desired locations for placement of the pressure cuff are the wrist, above and or below the elbow, and such other locations as may be found to be effective. When placed on the arm, the location of the cuff will typically be within about 5 inches above or below the elbow. When placed on the wrist, the location of the cuff will typically be within about 3 inches of the base of the hand. The location of the pressure cuff may be dependent upon the location of the tremor which it is desired to control or suppress. More than one cuff may be used simultaneously, e.g., one on the wrist and one above and/or below the elbow.
The desired amount of pressure is, because of patient differences, a wide range of pressure, but an effective tremor suppressing pressure can easily be determined empirically, simply be observing the effect on the patient as pressure is applied and increased to the appropriate level. The duration of pressure application is similarly determined empirically. Tremor suppression in legs can be accomplished in the same manner by applying pressure to the area above the ankle or the area above or below the knee. The location, amount and duration of pressure are determined empirically.